lmkd: Prevent killing foreground processes due to thrashing

Page cache thrashing affects device performance and by killing a process
we try to stop it. However if the thrashing application is the one which
user is interacting with then lmkd should not kill it even though it might
affect device performance.

Bug: 141286980
Test: SequentialRWTest CTS test
Change-Id: If86c0e7e8ad9adf1816659562151ca083eaa65c4
Signed-off-by: Suren Baghdasaryan <surenb@google.com>